1. Field of the Invention
This invention relates to a thermal printer.
2. Description of the Prior Art
Japanese published unexamined patent application No. 60-90781 discloses a color thermal printer in which different colors of information are sequentially recorded by a thermal head on a recording paper. The printing density or depth depends on the temperature of the thermal head and is subject to the color of ink. Accordingly, the thermal head is preheated by a heater to a temperature adequate to each color of ink. In this prior art printer, during the start of the activation of the thermal head to print each color of information, the temperature of the thermal head tends to deviate from a desired preheating range due to a self-heating effect. Such a temperature deviation causes an undesirable variation in the printing density.